Crosslinkage of cellulose fibers with phosphate esters of di-ethanol sulfones



United States Patent. OfiEice This invention relates to a method for improving the properties of fibrous material, and more particularly to a method for improving (i.e. increasing, rendering more permanent, etc.) dimensional and shape retention properties variously referred to as wet and/or dry crease resistance, crease angle retention, crease recovery, wrinkle resistance, wrinkle recovery, dimensional stability, washand-wearability, swelling resistance, shrinkage resistance, tensile strength, retention of creases, pleats, glazed, em-

bossed and other mechanical defects, and the like, in

addition to other properties such as resistance to attack by moths, mildew and the like, washing, laundry bleaches and sours, chlorine retention, industrial gases and other environmental conditions, development of objectionable odors, yellowing or other discoloration, hydrolysis, heat and/or abrasion, and the like. lates to improved fibrous material produced by such method.

Crease resistant finishing agents for fibrous material, particularly cellulosic material such as cotton, have recently become very popular and a large proportion of such material now provided to the trade have been treated With such agents for the production of so-called wash and wear effects and the like. Most such agents have up to the present been resinous, which involves a number of disadvantages including unduly high costs, a tendency to stiffen and otherwise undesirably change the character and properties of the fibrous material and the like. Further, considerable room for improvement of such agents remains with respect to other fiber properties of the type referred to above.

In U.S. Patent 2,524,399 there is disclosed a shrinkproofing and crease-proofing process involving the reaction of a cellulose fiber with divinyl sulfone. Although this process is considered to be non-resinous, thereby eliminating some of the aforementioned disadvantages, it is subject to a number of other objections which have prevented its commercial adoption. The most important objection to this process resides in the fact that divinyl sulfone is a very active skin vesicant and lachrymator whereby its use in commercial operations, even with specialized more costly equipment, is extremely hazardous. Another objection to this patented process is its failure to produce any substantial improvements in dry crease resistance of the treated cellulose fibers.

It is an object of this invention to provide a process for improving the properties of fibrous material which will not be subject to one or more of the above disadvantages. Another object of this invention is the provision of improved fibrous material treated by such a process. Other objects and advantages will appear as the description proceeds.

The attainment of the above objects is made possible by this invention which comprises reacting fibrous material in the presence of an alkaline catalyst with a water soluble substance which liberates divinyl sulfone in the presence of such catalyst. Generally, the substance liberating divinyl sulfone is applied to the fibrous material from an aqueous medium, and the alkaline catalyst may be applied to the fibrous material before, after, or simultaneously (e.g. dissolved in the same aqueous medium) with the said substance liberating divinyl sulfone. It has The invention also re- I 3,314,744 Patented Aprt 18, 1967 been further found that substantial and unexpectedly improved dry crease resistance is imparted to the fibrous material if, following treatment of the fibrous material in the presence of an alkaline catalyst with said substance liberating divinyl sulfone, the treated material is, without washing, directly dried and cured at a temperature of at least about 220 F. It has been found that the process of this invention enables the attainment of substantially permanent effects with respect to improved properties of the above described type, while greatly reducing or eliminating completely the hazards connected with the use of divinyl sulfone itself.

In accordance with the preferred method of carrying out the present process, the substance liberating divinyl sulfone is applied to the fibrous material. in the form of an aqueous medium which may be a solution, emulsion, suspension or other type of dispersion at any temperature ranging from room temperature to the boiling point of the medium. The alkaline reacting catalyst, whether applied before, after, or simultaneously with the substance liberating divinyl sulfone, is generally applied from an aqueous medium at a concentration sufiicient to yield a pH of about 7.5 to 10.5 or more. Such concentration may range from less than 0.5% up to 8% or more. As the alkaline reacting catalyst, there is preferably employed an alkali metal (sodium, potassium, lithium, etc.) hydroxide, carbonate, bicarbonate, phosphate, silicate, borate, acetate or the like. The alkali metal carbonates are preferred. Other alkaline reacting substances may be employed, including sodium sulfide, dipotassium tartrate, disodium'phthalate, or an organic base such as triethanolamine or the like. The concentration of the substance liberating divinyl sulfone in the above described aqueous medium is not particularly critical and may range from about 0.5 to 60% or more depending upon the manner of application to the fibrous material, the character of the fibrous material, the properties desired, and the like. This aqueous medium may be applied to the fibrous material by immersion, padding, spraying, printing or any other desired manner, continuously or otherwise. For overall ellects, it is preferred to apply an excess of the aqueous medium followed by a squeezing step with a liquor pickup of about 30% or less to or more by weight of the fiber. For printing or other decorative purposes the aqueous medium may be appropriately thickened in known manner. In general, optimum dimensional and shape retention properties are obtained by so conducting the process as to provide the fibrous material with about 1 to 10% of divinyl sulfone by weight of the material.

The preferred substances liberating divinyl sulfone in the presence of an alkaline catalyst are the reaction products of divinyl sulfone with a polybasic inorganic acid such as sulfuric, phosphoric or boric acid, or with an organic monocarboxylic acid such as formic, acetic, normal and isomeric propionic and butyric, benzoic acid or the like. The reaction between the divinyl sulfone and the .acid is an addition reaction whereby the resulting reaction products are structurally monoor preferably diesters (depending upon whether one or two moles of acid are employed per mole of divinyl sulfone) of 2,2'-sulfonyldiethanol. In fact, the defined reaction products are preferably made in this manner, namely by reaction of 2,2 sulfonyldiethanol with one of the aforementioned acids in free form or in the form of the anhydride, chloride, or complex. Thus, the esterification may be carried out with such ester'ifying agents as chlorosulfonic, sulfamic, sulfuric, phosphoric, boric acid or anhydride, sulphur trioxide, phosphorus pentoxide, sulfuryl chloride, phosphorus oxychloride, phosphorus pentachloride or the like. When a properly substituted acid or acid mixture is employed in the este-rification such as sulfamic acid, ammonium bisulfate, and the like, a water soluble or dispersible salt of the ester is directly produced. Complexes of some of the above acids and anhydrides may be employed as for example a combination of sulphur trioxide or chlorosulfonic acid with an ether such as dioxane, thioxane or 3,5- diohlorodiethylether, or with a tertiary nitrogen base such as pyridine or triethylamine. The resulting esters may be used as substances liberating divinyl sulfone in their free form or in. the form of their alkaline metal salts, e.g. sodium, potassium, lithium.

Another group of substances liberating divinyl sulfone in the presence of an alkaline-reacting catalyst are the monoand, preferably, diquaternary ammonium salts formed by reaction in ethanol or similar solvent of divinyl sulfone with soluble tertiary amine salts of inorganic acids such as sulfuric, phosphoric, or preferably hydrochloric acid. Less preferably, there may be employed the 1,4-thiazanium diozide monoquaternary ammonium salts formed by similar reaction of divinyl sulfone with water. soluble secondary amine salts of the same acids. Still less preferably, there may be employed the monoor ditertia-ry amines formed by reaction in aqueous medium of divinyl sulfone with water soluble secondary amines. As examples of such water soluble secondary and tertiary amines, there may be mentioned piperidine, pyridine, morpholine, N-methylmorpholine, picoline, quinoline, N-methyland N-cyclohexyl-N-methyl-taurine and -sarcosine, diand tri-methylamine, -ethylamine, -butylamine, -eth'anolamine, -propanolamine, and the like.

Other substances liberating divinyl sulfone in the presence of an alkaline reacting catalyst are the sulphur analogs of the above described esters of 2,2-sulfonyldiethanol with polybasic inorganic or organic monocarboxylic acids, as for example the divinyl sulfone Bunte salt of the formula The preparation of this compound by reaction of divinyl sulfone with sodium thiosulfate is disclosed by Sta-hmann et al., J. Org. Chem. 11, 719-735 (1946). This same article also discloses the production of a number of the above described reaction products of divinyl sulfone with amines and amine salts.

These and other substances liberating divinyl sulfone in the presence of an alkaline reacting catalyst in the aqueous treating medium and/or during the subsequent preferred curing treatment, are operative in the present process. Since the reaction of the liberated divinyl sulfone with the fibrous material requires the presence of an alkaline catalyst, it will be understood that in order to maintain the conditions of catalyst concentration and pH referred to above, additional quantities of alkaline catalysts must be added molecularly equivalent to the amount of acid liberated from most of the above described substances which liberate divinyl sulfone in the presence of such catalysts. Thus, those of the above described substances which are diquaternary ammonium salts or diesters (or their sulphur analogs such as the Bunte salt) will require the use of two molar equivalents of alkaline catalyst per mole of such substance in excess of the amount of catalyst necessary to catalyze the reaction between the liberated divinylsulfone and the fibrous material. Similarly, the above described monoquaternary salts and monoesters will require an excess of one mole of alkaline catalyst per mole of such substance. The tertiary amine substances liberating divinyl sulfone need no excess of alkaline catalyst since they liberate no acid.

Following application of the substance liberating divinyl sulfone and alkaline reacting catalyst to the fibrous material, the treated material is in accordance with the preferred embodiment herein directly dried without washing and then cured at a temperature of at least about 220 F. It has been found that this during step enables the attainment of unexpectedly improved dry crease resistance. The duration of the curing will generally vary inversely with the temperature, although of course both temperature and duration will depend upon the fibrous material being treated, the results desired, etc. In general, the curing step will usually range up to 10 minutes or more at 220 F. to as little as 15 seconds or less at 500 F. Too high a curing temperature and/or duration causes fiber damage and is to be avoided. These maximum permissible conditions are readily determinable in any particular instance.

Following the curing step, which may of course be omitted if desired as for example in the production of high wet strength paper, the treated fibrous material may be simply washed and/or bleached in known manner with the usual oxidizing agents such as sodium hypochlorite, hydrogen peroxide, and the like. For white materials it is usually desirable to apply a bleaching treatment to the cured fibrous materials directly, or, if desired, after an intermediate washing.

The process of this invention may be applied to the fibrous material in the natural state (unbleached), or to such material which has been bleached white or colored in any manner and with any desired dyestuff or pigment. The alkaline curing step required in the present process often results in discoloration or yellowing of the fibrous material. This is particularly troublesome in the processing of white fibrous material. In accordance with the expedient disclosed and claimed in the oopending application of Freyermuth and Mayhew, Ser. No. 96,604, filed March 20, 1961, such discoloration can be minimized or eliminated by including in the aqueous alkaline medium a boron-containing compound.

The mechanism by which such boron-containing compounds function to reduce discoloration is difiicult to postulate in view of the fact that perborate compounds are considered to have an oxidizing effect, alkali metal borohydrides .are reducing agents, and alkali metal tetraborates such as borax are neither. The nature of the [boron-containing compound employed to reduce discoloration is accordingly immaterial. Thus, there may be employed boric acid and tluoroboric acid and their metal, ammonium and amine salts, and boron fluoride addition products with such compounds as diethyl ether, water, lower alcohols such as methanol, ethanol, propanol, and the like, ammonia, aliphatic and aromatic amines such as ethylamine, aniline and the like, canboxylic acids such as acetic, propionic, stearic and lbenzoic and the like, amides such as acetamide, propionamide and the like, and phenols, thiophenols, cresols, naphthols, and the like.

A preferred group of boron-containing compounds operative herein are the ammonium, amine and metal (including also alkaline earth metal and alkali metal) borates such as the metaborates, perborates, and tetraborates. The alkali metal .borates such as those of sodium and potassium are preferred because of their economy, availability, solubility properties, etc. Other such operative boroncontaining compounds are the borates of aliphatic, aromatic and heterocyclic amines such as mono-, diand trirnethylamine, -e-thylamine, -propylamine, -butylamine, -octylamine, -cyclohexylamine, mono-, di-, and tri-ethanolamine, -propanolamine, -butanolamine, and -octanolamine, morpholine, piperidine, pyridine, and the like, and metal-s such as calcium, magnesium, zinc, manganese, aluminum, barium, coper, iron, nickel, tin, and the like.

Another referred 'grou of boron-containing co-mounds are the borohydrides of the same cations as referred to in the preceding paragraph with respect .to the borates. Those preferred are the alkali metal borohydrides, particularly sodium borohydride.

The above described boron-containing compound is applied to the fibrous material together with the substance liberating divinyl sulfone and/ or alkaline reacting catalyst in an amount sufiicient to obtain the desired reduction in discoloration which amount will be readily ascertainable in any particular instance by routine experimentation. Usually, an aqueous medium containing about 0.03 to 5% of the boron-containing compound will suffice in most instances. The borohydrides are extremely effective in relatively small amounts in the lower part of the aforementioned range and may be employed in concentrations of about 0.03 to 0.08%. The borates are generally employed in higher concentrations of about 0.1 to preferably about 0.1 to 1%.

The present process may also be advantageously employed for simultaneously dyeing the fibrous material With a reactive dyestuff. Such dyestuffs may be of any type, inorganic but generally organic, containing a reactive atom or group capable of reacting with the fiber being treated in the presence of an alkaline reacting catalyst. As examples of classes of such reactive dyestuffs, which may be nitro dyestuffs, dyestuffs of the azo, anthraquinone, phthalocyanine or any other series, including inorganic, which dyestulfs may be metal free or may contain metal in complex union, there may be mentioned dyestuffs containing an s-triazinyl radical carrying one or two chlorine or bromine atoms directly attached to the triazine ring,

fi-halogenopropionyl, fi-haloethylsul fonyl, ,Ekhalogenoe'thylsulfamyl, -sulfatoethylsulfonyl, fl-phosphatoethylsulfonyl, fi-acyloxyethylsulfonyl, B-hydroxyethylsulfonyl, chloroacetylamine, 5 (chloromethyl)-fi-sulfatoethyl-sulfamyl, vinyl sulfone, alkyl phosphite, or sulfon fluoride radical. .Such radicals, particularly those containing a sulfonyl group, may if desired be nuclearly substituted either directly to the sulfonyl group or through amethylene or other linkage. Specific examples of such dyestuffs are described in British No. 209, f land 2, British No. 298,484 in Example 1, British Nos. 456,343, 460,224, 733,471, 740,533, 775,308,772030,

774,925, 780,591, 781,930, 785,120, and 785,222; French Nos. 901,187 and 907,103; Belgian Nos. 497,065, 543,214, 543,215, 543,216, and US. Nos. 1,935,929, 2,151,857, 2,424,493, 2,434,150, 2,657,205, 2,670,265, 2,728,762, 2,743,267, 2,766,231, 2,784,204, etc. US. 2,895,785 also discloses methods for dyeing textiles with reactive dye stuffs followed by an alkaline heating step.

For simultaneously dyeing the fibrous material as described above, a suitable amount of reactive dyestuff is applied together with the substance liberating divinyl sulfone and/or alkaline reacting catalyst and the process otherwise carried out unchanged. The concentration of reactive catalyst to be included in the aqueous medium is of course a matter of choice obvious to skilled dyers, and may range from about 0.05 to 3 or 4% by weight of the fibrous material depending upon the dyestuff, the fibrous material, the shade desired, etc.

The mechanism by which the process of this invention yields the desired i1 proved properties apparently involves a cross-linking reaction between one molecule of divinyl sulfone and two reactive sites in the fiber molecules, during the application of the substance liberating divinyl sulfone and alkaline reacting catalyst and/ or during the subsequent curing step. Most effective reaction and cross-linking occurs with hydroxy groups in fibrous material such as cellulose, polyvinyl alcohol, partially hydroylzed polyvinyl acetate and cellulose acetate and the like. Reaction also occurs with other fibers containing reactive or replaceable atoms or groups such as hydrogen or halogen or the like, or with fibers containing unsaturated linkages.

The process of this invention has been found to be highly effective for improving the properties of cellulosic fibers of natural or synthetic type such as cotton, linen, Wood, paper, regenerated cellulose and the like. The fibrous material may be in any of the usual forms and in natural bulk, interwoven, knitted, or felted form as for example in the form of staple fiber or continuous filaments in bulk form or in the form of tow, rope, yarns, slubbings, warps, fabrics, felts, and the like, and treated as a wound package, running length, fibrous stock, bulk, etc. In addition to cellulose and its derivatives, the process of this invention may be employed for improving other fibers, including natural and synthetic proteinaceous fibers such as wool, silk, leather, animal hides and skins, casein, as nylon and polypyrrolidone, polyurethanes, polyesters, copolymers or homopolymers containing recurring carboxylic or cyano groups, polyvinyl alcohol, partially hydrolyzed cellulose acetate and polyvinyl acetate, polyvinyl chloride, and mixtures, copolymers and graft polymers thereof. Mixed fabrics and fibers may likewise be so treated. The process of the present invention finds its greatest advantage in the treatment of white felts and woven fabrics, particularly cotton shirting, sheetlwear, apparel, and the like. When employed for simultaneously dyeing the material, brighter, truer and faster'shades of dyeings are obtainable. When applied to previously dyed or pigmented material, improved fastness properties are obtainable.

It will be understood that the present process may be applied to fibrous material in conjunction with other substances in addition to the functional agents described above, as for example optical brighteners, stabilizers, softeners, surface active agents, reactive bacteriostats, finishes such as starch, polyvinyl alcohol and the like. Previous or simultaneous treatment of the fibrous material with such a finish enables more permanent effects due to simultaneous reaction or cross-linking of the divinyl sulfone therewith.

The following examples are only illustrative of the present invention and are not to be regarded as limitative. All parts and proportions referred to herein and in the appended claims are by Weight unless otherwise indicated.

Example I 72.0 g. 2,2'-sulfonyldiethanol were melted by heating to C; in a three necked flask equipped with a stirrer,

thermometer and an electric heating mantle. The molten mixture was allowed to super cool to 50 C. and 52.5 g. phosphorus pentoxide were added portion-Wise during one hour. at 50-55" C. The temperature was gradually increased to C. during one-half hour. The temperature increased to 190 C. due to the exothermic reaction. Cooling by an ice-bath brought the temperature down to 54 C. ml. Water were added to dissolve the reaction product. The pH was raised from 1.0 to 6.2 by the gradual addition of 106.5 g. sodium bicarbonate. 435 ml. water were added to completely dissolve the mixture. The solution Was clarified by the addition of activated charcoal. 763 g. of an approximately 10% solution of the diphosphate ester of 2,2-sulfonyldiethanol was obtained.

Sodium carbonate was added to the solution which was then immediately padded on 80 x 80 cotton sheeting to deposit 5% of the diphosphate ester and 2% of sodium carbonate. After drying and heat curing at 300 F. for 3 minutes, the treated cloth when tested by A.S.T.M. test method D1295-53T, had a dry crease recovery angle of 218 and a wet crease recovery angle of 222. The procedure was repeated using 2% sodium bicarbonate in place of 2% sodium carbonate. Dry and wet crease recovery angles of 212 and 220 respectively were obtained.

Example 11 A mixture of 15.4 g. 2,2'-sulfonyldiethanol, 19.4 g. sulfamic acid and 3 ml. ethanol was heated on a hot plate to 100 C. with mechanical stirring, then a magnetic stirrer was used. The temperature was raised gradually to 120 C. then to -155 C. Anexothermic reaction was observed. After 10 minutes at 150-155 C. the melt was cooled to room temperature. 3-0 ml. Water were added and the glass-like material was dissolved. The pH was raised from 1.5 to 6.6 by the addition of 1.53 g. sodium bicarbonate. 66.3 g. of solution containing the diammonium salt of the bis-sulfate ester of 2,2'-sulfonyldiethanol was obtained.

A solution containing 21.7% by weight of the above diammonium salt and 6.0% by weight sodium carbonate was padded at 80% wet pick-up on 80 x 80 cotton sheeting. The treated fabric was dried at 180 F. and cured in a steamer at 220 F. for 1 minute. The washed and dried fabric exhibited crease recovery angles of 210 dry and 196 wet when tested by A.S.T.M. test method D1295-53T.

Example 111 A mixture of 47.2 g. 2,2'-sulfonyldiethanol and 67.3 g. acetic anhydride was heated (95 C.) with stirring in steam bath for 12 hours. The acetic acid was then distilled from the reaction mixture. 27 ml. water were added to the residue and the pH was raised from 5.7 to 6.6 by the addition of 0.7 ml. 20% sodium carbonate solution. Sufficient water was added to make a total of 134 g. solution of the diacetate ester of 2,2'-sulfonyldiethanol.

An acetone solution containing 10% by weight of the above diacetate ester was padded on 80 x 80 cotton sheeting. The fabric was dried and immersed in an aqueous bath containing 1% sodium hydroxide and 5% sodium sulfate at room temperature and was then rolled up and allowed to stand for one hour. The fabric was rinsed in dilute acetic acid bath, washed and dried. The treated fabric showed improvement in crease recovery properties.

This invention has been disclosed with respect to certain preferred embodiments and it is to be understood that various modifications and variations thereof obvious to persons skilled in the art are to be included within the spirit and purview of this invention and the scope of the appended claims.

I claim:

1. A process for improving the properties of cellulose textile fibrous material without altering the fiber structure thereof comprising reacting said material under alkaline conditions with the phosphate ester of 2,2-sulfonyldiethanol.

2. A process for improving the properties of cellulose textile fibrous material without altering the fiber structure thereof comprising treating said material with an aqueous alkaline medium containing the diphosphate ester of 2,2- sulfonyldiethanol, and then drying and curing the treated material at a temperature of at least about 220 F.

3. A process as defined in claim 2 wherein said aqueous medium contains a boron-containing compound selected from the group consisting of metal, ammonium and amine borates and bo'rohydrides.

4. A process as defined in claim 3 wherein said boroncontaining compound is sodium tetraborate.

5. A process as defined in claim 3 wherein said boroncontaining compound is sodium borohydride.

References Cited by the Examiner OTHER REFERENCES Stahman: J. of Org. Chem, Mar. 22, 1946, pp. 719- 735.

Tesoro: Textile Research 283295.

Borghetty et al.: Amer. Dyestuff Reporter, pp. 3437.

1., April 1961, vol. 31, pp.

Feb. 4, 1963,

NORMAN G. TORCHIN, Primary Examiner.

MORRIS O. WOLK, ABRAHAM WINKELSTEIN,

Examiners. 

1. A PROCESS FOR IMPROVING THE PROPERTIES OF CELLULOSE TEXTILE FIBROUS MATERIAL WITHOUT ALTERING THE FIBER STRUCTURE THEREOF COMPRISING REACTING SAID MATERIAL UNDER ALKALINE CONDITIONS WITH THE PHOSPHATE ESTER OF 2,2''-SULFONYLDIETHANOL. 